U.S. patent number 6,654,209 [Application Number 09/955,776] was granted by the patent office on 2003-11-25 for low resistance lead structure for a low resistance magnetic read head.
This patent grant is currently assigned to Seagate Technology LLC. Invention is credited to Billy Wayne Crue, Gregory John Parker, Michael Allen Seigler, Petrus Antonius Van der Heijden.
United States Patent |
6,654,209 |
Seigler , et al. |
November 25, 2003 |
Low resistance lead structure for a low resistance magnetic read
head
Abstract
A magnetic recording head includes a current perpendicular to
the plane read head having a read sensor and a low resistance lead
structure. The lead structure includes a layer of conductive
material that forms at least a portion of the lead structure such
that the layer of conductive material has a lower resistivity than
a resistivity of the remainder of the lead structure. The layer of
conductive material with lower resistivity decreases the overall
resistance of the lead structure.
Inventors: |
Seigler; Michael Allen
(Pittsburgh, PA), Van der Heijden; Petrus Antonius
(Cranberry Township, PA), Parker; Gregory John (Warrendale,
PA), Crue; Billy Wayne (Pittsburgh, PA) |
Assignee: |
Seagate Technology LLC (Scotts
Valley, CA)
|
Family
ID: |
26948149 |
Appl.
No.: |
09/955,776 |
Filed: |
September 19, 2001 |
Current U.S.
Class: |
360/322;
G9B/5.116; G9B/5.114; 360/319 |
Current CPC
Class: |
B82Y
10/00 (20130101); G11B 5/3903 (20130101); B82Y
25/00 (20130101); G11B 5/3967 (20130101); G11B
2005/3996 (20130101) |
Current International
Class: |
G11B
5/39 (20060101); G11B 005/39 () |
Field of
Search: |
;360/322,319,317,324.1,324.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Evans; Jefferson
Attorney, Agent or Firm: Queen, II; Benjamin T. Pietragallo,
Bosick & Gordon
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of United States Provisional
Application No. 60/260,712 filed Jan. 10, 2001.
Claims
What is claimed is:
1. A current perpendicular to the plane read head, comprising: a
read sensor; and a lead structure positioned adjacent said read
sensor, said lead structure including an integrally formed
lead/magnetic shield layer and a layer of conductive material
having a lower resistivity than a resistivity of the lead/magnetic
shield layer, said lead/magnetic shield layer and said layer of
conductive material structured and arranged to provide parallel
sense current paths in at least a portion of said lead/magnetic
shield layer and a corresponding portion of said layer of
conductive material.
2. The read head of claim 1, wherein said layer of conductive
material is a material selected from the group consisting of Cu,
Au, Ag, Ta, Cr and Rh.
3. The read head of claim 1, wherein said layer of conductive
material is proximate to said read sensor.
4. The read head of claim 1, wherein said layer of conductive
material is in contact with said read sensor.
5. The read head of claim 1, wherein said read sensor is a giant
magnetoresistive sensor.
6. The read head of claim 1, wherein said layer of conductive
material has a thickness in the range of 100 to 10,000
angstroms.
7. The read head of claim 1, wherein said lead structure includes
an additional layer of conductive material that forms another
portion of said lead structure.
8. The read head of claim 1, further comprising an additional lead
structure positioned adjacent said read sensor such that said read
sensor is between said lead structure and said additional lead
structure.
9. A current perpendicular to the plane read head, comprising: a
read sensor; and a lead structure positioned adjacent said read
sensor, said lead structure including means for providing parallel
sense current paths in at least corresponding portions of said lead
structure that have differing resistivities for reducing the
resistivity of said lead structure.
10. A read head for a magnetic disc storage system, comprising:
first and second lead structures each including an integrally
formed lead/magnetic shield layer and a layer of conductive
material having a lower resistivity than the resistivity of the
lead/magnetic shield layer, said lead/magnetic shield layer and
said layer of conductive material structured and arranged to
provide parallel sense current paths in at least a portion of said
lead/magnetic shield layer and a corresponding portion of said
layer of conductive material; and a current perpendicular to the
plane read sensor between the first and second lead structures.
11. The read head of claim 10, wherein said layers of conductive
material are a material selected from the group consisting of Cu,
Au, Ag, Ta, Cr and Rh.
12. The read head of claim 10, wherein said layers of conductive
material are proximate to said read sensor.
13. The read head of claim 10, wherein said layers of conductive
material are in contact with said read sensor.
14. The read head of claim 10, wherein said read sensor is a giant
magnetoresistive sensor.
15. The read head of claim 10, wherein said layers of conductive
material have a thickness in the range of 100 to 10,000
angstroms.
16. The read head of claim 10, wherein each said lead structure
includes an additional layer of conductive material that forms
another portion of said lead structures.
17. A read head for a magnetic disc storage system, comprising:
first and second lead structures, at least one of said first and
second lead structures including means for providing parallel sense
current paths in at least corresponding portions of said lead
structure that have differing resistivities for reducing the
resistivity of said first and second lead structures; and a current
perpendicular to the plane read sensor between the first and second
lead structures.
18. A magnetic recording head, comprising: a magnetic sensor
element; and a lead structure positioned adjacent said read sensor,
said lead structure including an integrally formed lead/magnetic
shield layer and a layer of conductive material having a lower
resistivity than a resistivity of the lead/magnetic shield layer,
said lead/magnetic shield layer and said layer of conductive
material structured and arranged to provide parallel sense current
paths in at least a portion of said lead/magnetic shield layer and
a corresponding portion of said layer of conductive material.
19. A magnetic disc drive storage system, comprising: a housing;
and a rotatable magnetic storage medium positioned in said housing;
and a movable recording head mounted in said housing adjacent said
magnetic storage medium, said recording head including a current
perpendicular to the plane read head comprising: first and second
lead structures each including an integrally formed lead/magnetic
shield layer and a layer of conductive material having a lower
resistivity than the resistivity of the lead/magnetic shield layer,
said lead/magnetic shield layer and said layer of conductive
material structured and arranged to provide parallel sense current
paths in at least a portion of said lead/magnetic shield layer and
a corresponding portion of said layer of conductive material; and a
current perpendicular to the plane read sensor between the first
and second lead structures.
20. A method of making a lead structure for a current perpendicular
to the plane read head, comprising: forming a first layer of said
lead structure as an integrally formed lead element and magnetic
shield; and forming on at least a portion of said first layer a
second layer having a lower resistivity than a resistivity of said
first layer, wherein said first layer and said second layer are
structured and arranged to provide parallel current paths in at
least a portion of said first layer and a corresponding portion of
said second layer.
21. A method of using a current perpendicular to the plane read
head to read data in a magnetic disc storage system, comprising:
providing a lead structure having an integrally formed
lead/magnetic shield layer and a layer of conductive material
having a lower resistivity than the lead/magnetic shield layer;
providing a read sensor adjacent said lead structure; and passing a
sense current through said lead structure and said read sensor such
that said sense current passing through said lead structure is
concentrated in said layer of conductive material having a lower
resistivity, said lead/magnetic shield layer and said layer of
conductive material structured and arranged to provide parallel
sense current paths in at least a portion of said lead/magnetic
shield layer and a corresponding portion of said layer of
conductive material.
22. The method of claim 21, further comprising forming said layer
of conductive material on said lead structure so as to focus said
sense current toward said read sensor.
Description
FIELD OF THE INVENTION
The invention relates to magnetic recording heads, and more
particularly, to a lead structure for a read head of such recording
heads.
BACKGROUND OF THE INVENTION
Devices utilizing the giant magnetoresistance (GMR) effect have
utility as magnetic sensors, especially as read sensors in read
heads used in magnetic disc storage systems. The GMR effect is
observed in thin, electrically conductive multi-layer systems
having magnetic layers. A type of magnetic sensor utilizing the GMR
effect is referred to as a "spin valve" sensor.
A spin valve sensor may include a sandwiched structure having two
ferromagnetic layers separated by a thin non-ferromagnetic layer.
One of the ferromagnetic layers is called the "pinned layer"
because it is magnetically pinned or oriented in a fixed and
unchanging direction. A common method of maintaining the magnetic
orientation of the pinned layer is through exchange coupling
utilizing a proximate, i.e. adjacent or nearby, anti-ferromagnetic
layer, commonly referred to as the "pinning layer." The other
ferromagnetic layer is called the "free" or "unpinned" layer
because its magnetization can rotate in response to the presence of
external magnetic fields.
The benefits of spin valve sensors result from a large difference
in electrical conductivity exhibited by the devices depending on
the relative alignment between the magnetizations of the GMR
element ferromagnetic layers. In order for antiferromagnetically
pinned spin valve sensors to function effectively, a sufficient
pinning field from the pinning layer is required to keep the pinned
ferromagnetic layer's magnetization unchanged during operation.
Various anti-ferromagnetic materials, such as PtMn, NiMn, FeMn,
NiO, IrMn, PtPdMn, CrMnPt, RuRhMn, and TbCo, have been used or
proposed as antiferromagnetic pinning layers for spin valve
sensors. GMR sensors can be used to sense information encoded in
magnetic storage media. In operation, a sense current is passed
through a read head of the magnetic disc storage system. The
presence of a magnetic field in the storage media adjacent to the
sensor changes the resistance of the sensor. A resulting change in
voltage drop across the sensor due to the change of the resistance
of the sensor can be measured and used to recover magnetically
stored information.
These sensors typically comprise a stack of thin sheets of a
ferromagnetic alloy, such as NiFe (Permalloy), magnetized along an
axis of low coercivity. The sheets may be mounted in the read head
so that, for example, the magnetic axes are transverse to the
direction of disc rotation for the pinned layer and parallel to the
plane of the disc for the free layer. The magnetic flux from the
disc causes rotation of the magnetization vector in at least one of
the sheets, which in turn causes a change in resistivity of the
sensor.
A read head for use in a disc drive can include a first shield, a
second shield, and a GMR sensor, or also referred to as a GMR
stack, located between the first shield and the second shield. For
operation of the sensor, a sense current is caused to flow through
the read head and particularly through the sensor. As resistance of
the sensor changes, the voltage across the sensor changes. This is
used to produce an output voltage.
The output voltage is affected by various characteristics of the
sensor. The sense current can flow through the sensor in a
direction that is perpendicular to the planes of the layers or
stack strips that comprise the sensor, i.e.
current-perpendicular-to-plane component or CPP, or the sense
current can flow through the sensor in a direction that is parallel
to the planes of the layers or stack strips, i.e. current-in-plane
or CIP. The CPP operating mode can result in higher output voltage
than the CIP operating mode. The higher the output voltage, the
greater the precision and sensitivity of the read head sensor in
sensing magnetic fields from the magnetic medium. Therefore, it is
desirable to maximize the output voltage of the read head and
specifically the sensor thereof.
Current perpendicular to the plane GMR sensors are known to have a
relatively low resistance. There have been three primary approaches
to overcoming the problem of low sensor resistance of CPP giant
magnetoresistance (GMR) sensors and allowing the GMR to be
measured. One approach uses superconducting contacts and measures
the GMR at low temperatures. A second approach involves making the
sensor or GMR stack very thick to raise its resistance. A third
approach involves making a very small sensor or GMR stack to
increase its resistance. The first two approaches are not practical
when it comes to the making of the CPP-GMR sensor for use in a
magnetic recording head. The disc drive cannot run at very low
temperatures nor can the sensor be more than 100's of nanometers
thick. The two main problems with the third approach relate to
manufacturing the small devices and achieving a low contact
resistance. The contact resistance is significant for small devices
since the contact resistance varies as the inverse of the sensor
area.
In addition to the importance of having a low contact resistance
between the lead and the sensor, it is also important to have a low
lead resistance leading up to this contact. Specifically, a
relatively high lead resistance will decrease the overall GMR
effect making the GMR more difficult to measure.
There is a need for an improved low resistance lead structure for a
magnetic recording head.
SUMMARY OF THE INVENTION
The invention meets the identified need, as well as other needs, as
will be more fully understood following a review of this
specification and drawings.
In accordance with an aspect of the invention, a current
perpendicular to the plane read head comprises a read sensor and a
lead structure positioned adjacent to read sensor. The lead
structure includes a layer of conductive material that forms at
least a portion thereof, wherein the layer of conductive material
has a lower resistivity than a resistivity of the remainder of the
lead structure. The layer of conductive material with lower
resistivity decreases the overall resistance of the lead structure.
By reducing the overall lead structure resistance, the read sensor
is allowed to more efficiently perform its intended function. In
order to decrease the overall resistance of the lead structure, the
layer of conductive material may be deposited on the lead structure
either proximate to the read sensor or positioned for contact with
the read sensor.
In accordance with another aspect of the invention, a current
perpendicular to the plane read head comprises a read sensor and a
lead structure positioned adjacent the read sensor. The lead
structure includes means for reducing the resistivity of the lead
structure.
In accordance with yet another aspect of the invention, a read head
for a magnetic disc storage system comprises first and second lead
structures and a current perpendicular to the plane read sensor
between the first and second lead structures. Each of the first and
second lead structures include a layer of conductive material that
forms at least a portion thereof. The layers of conductive material
have a lower resistivity than a resistivity of the remainder of the
first and second lead structures.
In accordance with a further aspect of the invention, a read head
for a magnetic disc storage system comprises first and second lead
structures and a current perpendicular to the plane read sensor
between the first and second lead structures. At least one of the
first and second lead structures includes means for reducing the
resistivity of the first and second lead structures.
In accordance with another aspect of the invention, a magnetic disc
drive storage system comprises a housing, a rotatable magnetic
storage medium positioned in the housing and a movable recording
head mounted in the housing adjacent the magnetic storage medium.
The recording head includes a current perpendicular to the plane
read head. The current perpendicular to the plane read head
comprises first and second lead structures and a current
perpendicular to the plane read sensor between the first and second
lead structures. Each of the first and second lead structures
include a layer of conductive material deposited on at least a
portion thereof to form the lead structures and the layers of
conductive material have a lower resistivity than a resistivity of
the remainder of the first and second lead structures.
In accordance with an aspect of the invention, a magnetic recording
head comprises a magnetic sensor element and a lead structure
positioned adjacent to the sensor element. The lead structure
includes a layer of conductive material that forms at least a
portion thereof, wherein the layer of conductive material has a
lower resistivity than a resistivity of the remainder of the lead
structure. The layer of conductive material with lower resistivity
decreases the overall resistance of the lead structure.
In accordance with an additional aspect of the invention, a method
of making a lead structure for a current perpendicular to the plane
read head comprises the steps of forming a first layer of the lead
structure as an integrally formed lead element and magnetic shield
and forming on at least a portion of the first layer a second layer
having a lower resistivity than a resistivity of the first
layer.
In accordance with a further aspect of the invention, a method of
using a current perpendicular to the plane read head to read data
in a magnetic disc storage system comprises providing a lead
structure having a layer of conductive material that forms at least
a portion thereof, the layer of conductive material having a lower
resistivity than the resistivity of the remainder of the lead
structure. The method further comprises providing a read sensor and
passing a sense current through the lead structure and the read
sensor. The sense current that is passed through the lead structure
is concentrated in the layer of conductive material having a lower
resistivity. The method may also include forming the layer of
conductive material on the lead structure so as to focus the sense
current towards the read sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial representation of a disc drive that can use a
low resistance lead structure constructed in accordance with this
invention;
FIG. 2 is an isometric sectional view of a portion of a read head
having a low resistance lead structure constructed in accordance
with this invention;
FIG. 3a is an isometric view of a portion of the read head
illustrated in FIG. 2.
FIG. 3b is an additional embodiment of the invention, similar to
the portion of a read head shown in FIG. 3a.
FIG. 3c is an additional embodiment of the invention, similar to
the portion of a read head shown in FIG. 3a.
FIG. 3d is an additional embodiment of the invention, similar to
the portion of a read head shown in FIG. 3a.
FIG. 4 is an isometric view of a further embodiment of a portion of
a read head constructed in accordance with the invention for
modeling aspects of the invention.
FIG. 5 is a graphical representation of measured current
distribution as modeled for the read head portion shown in FIG.
4.
FIG. 6 is a graphical illustration of the relationship between lead
resistance and read sensor area.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a low resistance lead structure for a
magnetic recording head, particularly suitable for use with a
magnetic disc storage system. A recording head is defined as a head
capable of performing read and/or write operations, or performing
magnetic sensor operations in general.
FIG. 1 is a pictorial representation of a disc drive 10 that can
utilize the lead structure and read head constructed in accordance
with this invention. The disc drive includes a housing 12 (with the
upper portion removed and the lower portion visible in this view)
sized and configured to contain the various components of the disc
drive. The disc drive includes a spindle motor 14 for rotating at
least one magnetic storage medium 16 within the housing, in this
case a magnetic disc. At least one arm 18 is contained within the
housing 12, with each arm 18 having a first end 20 with a recording
and/or read head or slider 22, and a second end 24 pivotally
mounted on a shaft by a bearing 26. An actuator motor 28 is located
at the arm's second end 24, for pivoting the arm 18 to position the
head 22 over a desired sector of the disc 16. The actuator motor 28
is regulated by a controller that is not shown in this view and is
well known in the art.
FIG. 2 is a cross-sectional view of a portion of a read head 22
constructed in accordance with this invention. The read head 22
includes first and second lead structures 30 and 32 positioned on
opposite sides of a read sensor 34. The read head 22 is configured
to fly adjacent to a magnet recording medium 16 having a plurality
of tracks, illustrated by tracks 36, 38. The tracks 36,38 contain
magnetic domains capable of storing digital information according
to the polarity of magnetization thereof and may provide for
longitudinal or perpendicular media recording. The magnetic domains
are illustrated by arrows, shown in track 38 only in FIG. 2. The
lead structures 30 and 32 are used to supply a constant current I
that flows through the lead structures 30 and 32 and the read
sensor 34 in a current perpendicular to the plane (CPP) direction.
When the read sensor 34 is subjected to an external magnetic field,
the resistance of the GMR stack that forms the read sensor 34
changes, thereby changing the voltage across the stack. The stack
voltage is then used to produce an output voltage. Alternatively, a
constant voltage may be applied and the current measured. In
addition, it will be appreciated that while the description set
forth herein is directed to a GMR type sensor, the invention is
also applicable to other type sensors such as magnetoresistance
(MR) sensors, inductive sensors, or other magnetic field sensors.
It will also be appreciated that the sensor 34 may be, for example,
a spin valve type sensor or a multilayer stack sensor having, for
example, a nx (magnetic/non-magnetic) multilayer arrangement.
The lead structure 30 includes an integrally formed lead element
and magnetic shield 40. The lead structure 30 also includes a layer
of conductive material 42 that forms at least a portion of the lead
structure 30. The lead structure 30 may also include an additional
layer of conductive material 44 that forms another portion of the
lead structure 30. Similarly, the lead structure 32 includes an
integrally formed lead element and magnetic shield 46 and a layer
of conductive material 48 that forms at least a portion of the lead
structure 32. The lead structure 32 may also contain an additional
layer of conductive material 50 that forms another portion of the
lead structure 32. It will be appreciated that lead structure 30 is
positioned relative to the read sensor 34 such that the current
flows through the lead structure 30 and into the read sensor 34.
The lead structure 32 is positioned relative to the read sensor 34
such that the current flows through the read sensor 34 and into the
lead structure 32. While lead structures 30 and 32 are shown in
FIG. 2 as being essentially identical, it will be appreciated that
lead structures 30 and 32 may be differently configured in
accordance with the invention.
In accordance with the invention, the layers of conductive material
42, 44 and 48, 50 are made of a material selected to have a lower
resistivity than a resistivity of the remainder of the lead
structures 30, 32, and specifically a lower resistivity of the
integrally formed lead element and magnetic shield 40 and 46 of
each lead structure. The integrally formed lead element and
magnetic shield 40 and 46 of each lead structure 30 and 32 may be
formed of, for example, NiFe and CoNiFe. Such materials, while not
necessarily having a relatively low resistance, do provide a
material that is both conductive and capable of providing magnetic
shielding. The layers of conductive material 42, 44 and 48, 50 may
be a material that is selected from the group, for example, Cu, Au,
Ag, Ta, Cr and Rh.
As described, the read head 22 illustrated in FIG. 2 is a CPP read
head having a read sensor 34, that may be a giant magnetoresistive
or magnetoresistance (GMR) type sensor. Such sensors are known to
have a relatively low resistance making the GMR more difficult to
measure. The overall lead resistance present in the lead structures
30 and 32 have a direct impact on the overall GMR from the read
sensor 34. Specifically, a relatively high lead resistance will
decrease the overall GMR effect making the GMR even more difficult
to measure. By constructing the lead structures 30 and 32 to
include one or more layers of conductive material 42, 44 and 48, 50
which have a lower resistivity than a resistivity of the remaining
portions of the lead structures 30 and 32, specifically a lower
resistivity than the integrally formed lead element and magnetic
shield portions 40 and 46, the overall lead resistance is
reduced.
FIG. 3a is a partial view of the read head 22 illustrated in FIG.
2. FIGS. 3b, 3c and 3d are views similar to FIG. 3a that illustrate
additional embodiments of lead structures 30b, 30c and 30d,
respectively, constructed in accordance with the invention.
Specifically, lead structure 30b includes an integrally formed lead
element and magnetic shield 40b. Lead structure 30b also includes
layers of conductive material 42b and 44b which have a lower
resistivity than the remainder of the lead structure 30b. The layer
of conductive material 42b is positioned adjacent or proximate to
the read sensor 34b. Similarly, lead structure 30c includes layers
of conductive material 42c and 44c with the layer 42c being
adjacent or proximate to read sensor 34c. In addition, lead
structure 30d, includes layers of conductive material 42d and 44d
with the layer of conductive material 42d being positioned adjacent
or proximate to the read sensor 34d. It will be appreciated that
the lead structures illustrated in FIGS. 3a -3d are examples of
differently configured lead structures constructed in accordance
with the invention, but that additional configurations of lead
structures may be utilized in accordance with the invention. The
layers of conductive material are formed as part of the lead
structure such that the layers of conductive material are, for
example, adjacent to the read sensor, proximate to the read sensor
and/or positioned for contact with the read sensor. Although not
shown in FIGS. 3b, 3c and 3d, it will be appreciated that
additional lead structures corresponding to lead structure 32
illustrated in FIGS. 2 and 3a may be provided such that the
additional lead structures not shown may have the same
configuration as the corresponding lead structures 30b, 30c and
30d, or the additional lead structures may have different
configurations in accordance with the invention.
Referring to FIGS. 4 and 5, the aspect of the invention for
decreasing the overall lead resistance in a lead structure will be
described in more detail. FIG. 4 is a partial view of a read head
122 constructed in accordance with the invention and modeled to
determine current distribution, as shown in FIG. 5, to illustrate
how the overall lead resistance can be reduced. Specifically, the
read head 122 includes a lead structure 130 having an integrally
formed lead element and magnetic shield 140 and a layer of
conductive material 144. The lead structure 130 was modeled by
applying a uniform potential of +V to the conductive material 144
and a uniform potential of -V where the representative read sensor
134 would be located.
Referring to FIG. 5 (wherein the numerous arrows represent the
direction of current flow between +V and -V), the current
distribution through the lead structure 130 is illustrated. For
reference purposes, a coordinate grid is shown at 160 for proper
orientation of the lead structure 130 in the graphical
illustration. The current is shown as staying primarily in the
layer of conductive material 144, which has a lower resistivity
than the integrally formed lead element and magnetic shield 140 of
the lead structure 130, until the current nears the end of the
layer of conductive material 144. The current then focuses toward
the representative sensor 134 and then enters the representative
sensor 134. Due to this focusing effect, the majority of the
resistance between +V and -V (i.e. lead structure resistance) comes
from the region near the representative sensor 134 where the
current focuses towards the representative sensor 134. This is a
result of the the area decreasing as the current focuses down
toward the representative sensor 134. The smaller the
representative sensor 134, the smaller the area in which the
current has to focus. While the current distribution has been
illustrated and described for lead structure 130, which is the lead
structure through which a current flows prior to entering the
representative sensor 134, it will be appreciated that essentially
the same principles apply to an additional lead structure from
which the current would leave the representative sensor 134 and
flow through.
FIG. 6 illustrates the lead resistance R as a function of sensor
area A. Once the sensor becomes small enough and the resistance is
dominated by the region where the current has to focus down, the
lead resistance varies approximately inversely with the sensor
area. Based upon these modeling results, it is evident that getting
a low resistivity material as close to the read sensor as possible
would be advantageous. This can be achieved by either making a
shield material that has a relatively low resistivity or by placing
a non-magnetic relatively low resistivity material near the read
sensor. However, placement of a low resistivity material close to
the read sensor must be done so as to maintain allowable
shield-to-shield spacing requirements. For differential sense read
sensors, where the linear density is not set by the
shield-to-shield spacing, the highly conductive non-magnetic
material could be inserted between the read sensor and the shield
without decreasing the maximum achievable linear density.
Accordingly, the low resistivity material is most advantageous when
positioned as close to the read sensor as possible without
jeopardizing the shielding capability of the shielding material
employed in the lead structure.
The invention also includes a method of making a lead structure,
such as lead structure 30, for a CPP read head, such as read head
22. The method includes forming a first layer of the lead structure
as an integrally formed lead element and magnetic shield, such as
the layer 40 of the lead structure 30. The method further includes
forming on at least a portion of the first layer a second layer,
such as the layer of conductive material 42 and/or 44, which has a
lower resistivity than a resistivity of the first layer. The layers
of the lead structure may be formed using, for example, standard
deposition or forming techniques. In accordance with the invention,
the second layer or layer of conductive material may have a
thickness in the range of 100 to 10,000 angstroms. In addition, the
layer of conductive material 42 and/or 44 may be configured in
different arrangements, such as shown, for example, in FIGS.
3a-3d.
The invention also includes a method of using a CPP read head such
as read head 22, to read data in a magnetic disc storage system,
such as the disc drive 10. The method includes providing a lead
structure, such as lead structure 30, having a layer of conductive
material, such as layer 42 and/or 44, that forms at least a portion
of the lead structure. The layers of conductive material, as
discussed herein, are a material selected to have a lower
resistivity than the resistivity of the remainder of the lead
structure. The method also includes providing a read sensor, such
as read sensor 34, adjacent to the lead structure. The method
further includes passing a sense current through the lead structure
and the read sensor such that the sense current passing through the
lead structure is concentrated in the layer of conductive material
which has a lower resistivity. The method may further comprise
forming the layer of conductive material of the lead structure so
as to focus the sense current toward the read sensor.
Whereas particular embodiments of the invention have been described
herein for the purpose of illustrating the invention and not for
the purpose of limiting the same, it will be appreciated by those
of ordinary skill in the art that numerous variations of the
details, materials and arrangement of parts may be made within the
principle and scope of the invention without departing from the
invention as described in the appended claims.
* * * * *